In order to meet the demand for wireless data traffic soring since the 4G communication system came to the market, there are ongoing efforts to develop enhanced 5G communication systems or pre-5G communication systems. For the reasons, the 5G communication system or pre-5G communication system is called the beyond 4G network communication system or post long term evolution (LTE) system. For higher data transmit rates, 5G communication systems are considered to be implemented on ultra high frequency bands (mmWave), such as, e.g., 60 GHz. To mitigate pathloss on the ultra high frequency band and increase the reach of radio waves, the following techniques are taken into account for the 5G communication system: beamforming, massive multi-input multi-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna, analog beamforming, and large scale antenna. Also being developed are various technologies for the 5G communication system to have an enhanced network, such as evolved or advanced small cell, cloud radio access network (cloud RAN), ultra-dense network, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-point (CoMP), and interference cancellation. There are also other various schemes under development for the 5G system including, e.g., hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) modulation (FQAM) and sliding window superposition coding (SWSC), which are advanced coding modulation (ACM) schemes, and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA), which are advanced access schemes.
The Internet is evolving from the human-centered connection network by which humans create and consume information to the Internet of things (IoT) network by which information is communicated and processed between things or other distributed components. Another arising technology is the Internet of everything (IoE), which is a combination of the Big data processing technology and the IoT technology through, e.g., a connection with a cloud server. To implement the IoT, technology elements, such as a sensing technology, wired/wireless communication and network infra, service interface technology, and a security technology, are required. There is a recent ongoing research for inter-object connection technologies, such as the sensor network, machine-to-machine (M2M), or the machine-type communication (MTC). In the IoT environment may be offered intelligent Internet Technology (IT) services that collect and analyze the data generated by the things connected with one another to create human life a new value. The IoT may have various applications, such as the smart home, smart building, smart city, smart car or connected car, smart grid, health-care, or smart appliance industry, or state-of-art medical services, through conversion or integration of existing information technology (IT) techniques and various industries.
Thus, there are various ongoing efforts to apply the 5G communication system to the IoT network. For example, the sensor network, machine-to-machine (M2M), machine type communication (MTC), or other 5G techniques are implemented by schemes, such as beamforming, multi-input multi-output (MIMO), and array antenna schemes. The above-mentioned application of the cloud radio access network (RAN) as a Big data processing technique may be said to be an example of the convergence of the 5G and IoT technologies.
In general, the mobile communication system has been developed to offer communication services while securing users' mobility. The sharp development of technology brought the mobile communication system to the stage of being able to offer high-speed data communication services as well as voice communication services.
Meanwhile, the 3rd generation partnership project (3GPP) is nowadays standardizing the LTE system as a next-generation mobile communication system. The LTE system is a technology for implementing high-speed packet-based communication to provide a transmission speed up to 100 Mbps that is higher than the data transmission rate being presently served.
Under vigorous discussion is the LTE-advanced (LTE-A) system that comes with various state-of-art technologies to present a further increased data rate. A representative example among the technologies to be newly adopted is carrier aggregation. Carrier aggregation, unlike in the conventional art where a user equipment (UE) performs data communication using only one forward carrier and only one backward carrier, enables one UE to use multiple forward carriers and backward carriers.
The current LTE-A standards define only intra-ENB carrier aggregation. This entails a low chance of applicability of carrier aggregation function, likely causing a failure to aggregate macro cells and pico cells, particularly, in the scenario where multiple pico cells and one macro cell are operated in an overlapping manner. The 3GPP Rel-12 goes on with a study called “small cell enhancement” to address such issues. Representative techniques the study aims to develop include inter-ENB carrier aggregation or dual connectivity technique between heterogeneous base stations (hereinafter, “dual connectivity”) that ensures a high data rate for one terminal by combining serving cells dependent upon other base station. Of course, vigorous discussion for other areas such as mobility backup proceeds, but the carrier aggregation technology used to be supported only within the base station is made available between the macro base station and pico or small cell base station, and this would have a significant influence on future communication technologies. Sharply increasing smartphone data usage would exponentially increase small cells to be deployed, and there would be a soring market share of small cell configurations using the legacy remote radio head (RRH) together with small cell base stations that may independently encompass terminals. Thus, when a terminal linked to a small cell receives data transmitted, the terminal may receive other types of data from a macro base station at the same time.
The small cell may operate on a higher frequency band as compared with the legacy macro cell, and the band available for small cells by 3.5 GHz have been already defined in the 3GPP standard. The band features that the available band is broader than the frequency band for the legacy macro cell and presents a poor transmission characteristic due to low transmittance but may enjoy an increased reception gain from a diversity effect obtained using multiple received radio waves coming from reflected waves. The 3.5 GHz band is available in some countries but not in other countries. The latter countries impose the requirement that the band should be dynamically used with a recognitive wireless technique that prevents the terminal or base station from interfering with the use of the band by the higher-priority user. Another noticeable trend is to apply cellular-related techniques for the unlicensed band used by WLAN or small-sized wireless devices, e.g., the LTE system. A need exists for addressing the co-existence issue that may arise due to a difference in operation from the WLAN when the LTE small cell uses the unlicensed band as carrier.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.